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Bijou All Tube Futterman Headphone Amplifier - Page 82

post #1216 of 3981
9/9/08 at 10:33pm
This just depends on how long life you want out of the components.

You'll have 10 tubes in the box for a fully balanced amp. Average 4W per tube for the heaters, that's 40W in the box from the tube heaters alone. Add another 5-10W for the rest of the stuff that's 45-50W.

So, just think about having a 50W bulb in the box.
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post #1217 of 3981
9/9/08 at 11:23pm
Quote:
Originally Posted by fishski13 View Post
pabbi1,
we expect a full report and pics of course .

re: chassis venting for an enclosed balanced Bijou. i'm looking at a Par-Metals 20-Series 19x12x5 enclosure and am wondering if i should ask for more vent holes on the top. the pic is standard with vents on sides, top, and bottom - another $20 for extra vents.

PACE
To emphasize Alex's point, this is what mine looks like, and I am VERY concerned with ventilation, even though there are holes over each tube. The Nabu is only 3.5" tall, no bottom vents, and no holes on the sides (yet)... short of some surplus MercuryCadmiumTelluride (used to cool the electronics in fighter jets), I'm really not sure what to do, except run her with the top down, and some security netting to keep my cats out of it... fans, a la the LD VI? Always something <sigh>.

ps - Ron, being conceived in New Orleans - during Mardi Gras, no less - don't think I hadn't already consulted with Marie Laveau on those attenuators. Voodoo and DIY are often eerily similar.
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post #1218 of 3981
9/10/08 at 2:04am
Alex and pabbi,
thanks. i will get the entire cover slotted with vents. the 5" height will help a bit too. i am also planning a custom faceplate from FPE that will more or less frame an acrylic window that will be spaced off/mounted on the backside with 1/8 off-sets, thus creating a continuous gap all around to create more ventilation. plus, i get to look at the glow of tubes .

this amp would be on the very top of my hi-fi shelf, well away from my 1 yr. old daughter. i have obvious safety concerns and would like to go with a totally enclosed chassis.

PACE
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post #1219 of 3981
9/10/08 at 2:37am
Quote:
Originally Posted by runeight View Post
say, amphead, great news on Pabbi1's amp. I was pretty sure that signal was not getting to the inputs. Thanks for working all of that out.

So, does it sound different from the single ended version of the amp?
More channel separation, and the differential noise canceling brings out detail somewhat. Spatial depth is increased. Sound is lush! ;-)
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post #1220 of 3981
9/10/08 at 7:29am
Where did you find a case big enough to house the balanced Bijou ?
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post #1221 of 3981
9/10/08 at 9:21am
[IMG][/IMG]

here's a layout for a balanced with a 16x12 boundary. the 370 DAZ transfo's will just squeeze in on the left. i assume dividers should be placed inbetween the transfo and rectifying stages, and the rectifying and output stages. how far apart do the transfos need to placed from one another to reduce flux interference and potential hum? maybe i should have gone with the vertical mount DAX and placed them at 90 deg to one another? i guess i could still mount the DAZ i've already bought vertically and get a DAZ for the second one. any suggestions?

the R-channel boards are mirrors of the L-channels, with the boards stuffed on the underside and flipped. the input wiring will dissect the two channels down the middle, with the input jacks and output jacks/potentiometers mounted directly in-line back to front respectively. the heater wiring feeds the outsides of the boards, with the R-channel heaters crossing the input signal perpendicular at only one point, right above the top boards of the L/R-channels.

i will try messing around with a lay-out for a 16x16 chassis. constructive criticism is appreciated .

PACE
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post #1222 of 3981
9/10/08 at 12:23pm
[IMG][/IMG]

here's a 16x12 layout i like a bit better. i can place one DAZ transfo between the two PS boards, with plenty of space behind for a second DAZ or DAX. i would then place only one divider between the PS/transfos and the amp boards.

my parts from Mouser should be here shortly. cleaning up the workbench for some soldering later on.

PACE
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post #1223 of 3981
9/10/08 at 12:50pm
You will want more room on the right hand side for (presumably) your input wiring, and may well consider the interior signal wiring as well. Looks like you will have plenty of room for some discrete pathways - a weakness with the Nabu case (at 18.5"x10" just barely enough room, forcing route compromises).

Otherwise, looks good...
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post #1224 of 3981
9/10/08 at 3:17pm
thanks pabbi!

yes, you're right, i will be using two TKD potentiometers and will have to space out the amp boards just a bit. i will have ample room for the XLR and RCA input jacks on the rear and using some shielded Mogami mic cable to the pots. the output jacks to the headphones will be mounted just below the pots. the 5" height should give me ample wiggle room as long as i can keep the input wiring to the pots "riding high" with a couple of tall threaded rods supporting mid-way, freeing up space below for the output wiring.

PACE
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post #1225 of 3981
9/10/08 at 4:20pm
fishski13, ideal balanced Bijou chassis size would work out to 11 x 19 x 4 inches. And if your stepped attenuator is large then 12 x 19 x 4 nches would be better. This would work out to 2 inches more width and 1 inch longer than Pabbi's case. And 1/2 inch taller. In the real world though, 12 x 20 would probably be easier to get. Edit: if you don't mind the case being really large, then about 4.5 inches tall or more will give you better ventilation. Edit: the balanced Bijou is certainly worth the large chassis size. Think old school Marantz style chassis. ;-)
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post #1226 of 3981
9/11/08 at 12:46am
Quote:
Originally Posted by amphead View Post
fishski13, ideal balanced Bijou chassis size would work out to 11 x 19 x 4 inches. And if your stepped attenuator is large then 12 x 19 x 4 nches would be better. This would work out to 2 inches more width and 1 inch longer than Pabbi's case. And 1/2 inch taller. In the real world though, 12 x 20 would probably be easier to get. Edit: if you don't mind the case being really large, then about 4.5 inches tall or more will give you better ventilation.
thanks. i've just realized that i'm going with some larger GenI Sonicaps at C3,4 and a GenII at C6, and will no doubt add others down the road. this amp could be a tweaker's delight, and i should provide more room for the amp boards. plus, going with 2 potentiometers instead of a single balanced attenuator makes things a bit tighter. at least the TKDs i'm buying have solder tabs, unlike the pain in the ass pins on a Blue Velvet, albeit at x4 the cost.

Par-Metals has an anodized 16x16x5 Series-20 for only $3.50 extra over the smaller $86 16x12 chassis - go figure. a divider is another $12. space isn't an issue. lead time is a week plus shipping. i may also just go with the cheaper black painted chassis since i'm going to be using an FPE faceplate anyway.

just finished whipping up the PS board. coming from a tube noob, and one that has only DIYed low voltage S.S., those 470u/450V Panny caps are HUGE!

PACE
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post #1227 of 3981
9/11/08 at 1:49am
The 16 x 16 will work just fine, but they claim to make any dimension you want. Looking at Pabbi's layout 16 inches for the long dimension might not allow for a "logical" layout. If It was me, I would get one that's 12 x 20 x 5.25 or even the one that they mention at 12 x 19 x 5.25 which is off the shelf and black anodized for ~$96.00. Or the one with less "bling" that is clear anodized in that dimension for ~$81.00. If I "pull the trigger" on a balanced Bijou, I will do the black anodized at 12 x 19 x 5.25 for my build. The only issue is whether or not they provide vents like they do on the 20 series.
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post #1228 of 3981
9/11/08 at 4:46am
Quote:
Originally Posted by amphead View Post
The 16 x 16 will work just fine, but they claim to make any dimension you want. Looking at Pabbi's layout 16 inches for the long dimension might not allow for a "logical" layout. If It was me, I would get one that's 12 x 20 x 5.25 or even the one that they mention at 12 x 19 x 5.25 which is off the shelf and black anodized for ~$96.00. Or the one with less "bling" that is clear anodized in that dimension for ~$81.00. If I "pull the trigger" on a balanced Bijou, I will do the black anodized at 12 x 19 x 5.25 for my build. The only issue is whether or not they provide vents like they do on the 20 series.
good call. i've thought about the 12 series, in those same dimensions as well. when i inquired about adding more vents to the 20 series on the top alone, they said it was a flat $20. i will call tomorrow about the cost to vent a 12 series and report back. their webite says that the 12 series has "Optional vent holes are available on top, bottom or sides." - i assume this to mean realitively cheap compared to a total custom job.

PACE
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post #1229 of 3981
9/11/08 at 6:51am
Pabbi, I have done the preliminary rewiring, without shielding on the pot to board wires. The shielding will be added tomorrow. So this is the first time anyone has heard a balanced Bijou with attenuators in both L/R channels. ;-) So....... whats the verdict? Orpheus owners would be plunking down some cash on a balanced Bijou. I'll risk putting it in the commercial grade category, at the upper 1 percent of gear out there. It absolutely kicks some serious axx! I have heard some really good gear in 2008 too, so my ears know what to listen for. Alex you really need one of these! Hard to believe that hacks can build something that compares so well with commercial gear. There is a real "intimacy" with the music that I can now appreciate with both attenuators installed. The attenuators really kicked it up a notch vs the Alps pots.
The sound is SPACIOUS!
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post #1230 of 3981
9/11/08 at 10:32am
Welcome to the dark side...

And with cheap tubes to boot.

There will be a couple of Texas head-fi meets (one in Austin even), so maybe Alex can get out for a listen... ;-)
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